Gasoline must be mixed with lubricating oil and then be sent into the cylinder of engine to be burned. In the prior art, lubricating oil was added into the gasoline tank directly and automatically mixed with gasoline. The mixed oil-and-gasoline was sent into the engine to be burned. However, adjusting the mixing rate of oil and gasoline was not very convenient. Thus, when the gasoline was added, the lubricating oil had to be added simultaneously. This was not a convenient operation either.
Therefore, it is the purpose of the present invention to mitigate and/or obviate the abovementioned problems in the manner set forth in the detailed description of the preferred embodiment.